This invention relates in general to universal joints for providing a driving connection between two members that are adapted to rotate about non-aligned axes of rotation. In particular, this invention relates to a method and an apparatus for facilitating the assembly of the components that make up such a universal joint.
Universal joints are well known devices that provide a driving connection between two members that are adapted to rotate about non-aligned axes of rotation. A typical universal joint includes a cross having a central body portion with four cylindrical trunnions extending outwardly therefrom. The trunnions are oriented in a single plane and extend at right angles relative to one another. A hollow cylindrical bearing cup is mounted on the end of each of the trunnions. Needle bearings or similar means are provided between the outer cylindrical surfaces of the trunnions and the inner cylindrical surfaces of the bearing cups to permit relative rotational movement therebetween. The bearing cups mounted on a first opposed pair of the trunnions are connected to a first yoke secured to an end of a first member, while the bearing cups mounted on a second opposed pair of the trunnions are connected to a second yoke secured to an end of a second member.
A full round end yoke is one type of yoke that is commonly used in a universal joint. A typical full round end yoke includes a body portion having a pair of opposed yoke arms extending therefrom. Each of the opposed yoke arms has a cylindrical opening formed in the end thereof. The two openings are co-axially aligned with one another, each extending between an outer surface and an inner surface of the associated yoke arm. To assemble the universal joint, two of the opposed trunnions of the universal joint cross (having no bearing cups mounted thereon) are initially inserted within the two openings formed through the yoke arms. Then, the bearing cups are moved axially inwardly through the openings from the outer surfaces of the yoke arms toward the inner surfaces thereof. In this manner, the bearing cups are installed over the ends of the opposed trunnions within the openings formed through the yoke arms. A pair of retainer clips or other retaining structures may then be secured to the full round end yoke to retain the bearing cups within the two openings formed through the yoke arms and on the associated trunnions.
During the assembly of the various components that make up the universal joint, it is important that the rotational center axis of the cross be precisely co-axially aligned with the rotational center axis of the yoke. If this co-axial alignment is not maintained, then undesirable rotational imbalances may be created within the universal joint. Such rotational imbalances can, if not corrected, result in the generation of undesirable noise and vibration when the universal joint is rotated during use. The correction of such imbalances usually involves the securement of one or more balance weights to the yoke, some other portion of the universal joint, or the driveshaft itself, which can result in undesirable additional time and expense during the assembly process. Thus, it would be desirable to provide an apparatus and method for facilitating the assembly of the components of a universal joint in such a manner that positions and maintains the rotational center axis of the cross co-axially aligned with the rotational center axis of the yoke during the assembly process.